INTERACTION OF OSA AND OBESITY ON THE INFLAMMATORY MARKERS
The Interaction of Obstructive Sleep Apnea and Obesity on the Inflammatory Markers C-Reactive Protein and Interleukin-6: The Icelandic Sleep Apnea Cohort
Erna S. Arnardottir, MS1,2,3; Greg Maislin, MS, MA3; Richard J. Schwab, MD3; Bethany Staley, RPSGT3; Bryndis Benediktsdottir, MD2; Isleifur Olafsson, PhD, MD1,2,4; Sigurdur Juliusson, PhD, MD5; Micah Romer, BS3; Thorarinn Gislason, PhD, MD1,2; Allan I. Pack, PhD, MB ChB2,3
1Department of Respiratory Medicine and Sleep, Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland; 2Faculty of Medicine, University of Iceland; 3Center for Sleep and Circadian Neurobiology and Division of Sleep Medicine/Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania; 4Department of Clinical Biochemistry, Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland; 5Department of Otolaryngology, Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland
To assess the relative roles and interaction of obstructive sleep apnea (OSA) severity and obesity on interleukin-6 (IL-6) and C-reactive protein (CRP) levels.
The Icelandic Sleep Apnea Cohort.
454 untreated OSA patients (380 males and 74 females), mean ± standard deviation age 54.4 ± 10.6 yr.
Measurements and Results:
Participants underwent a sleep study, abdominal magnetic resonance imaging to measure total abdominal and visceral fat volume, and had fasting morning IL-6 and CRP levels measured in serum. A significantly higher correlation was found for BMI than visceral fat volume with CRP and IL-6 levels. Oxygen desaturation index, hypoxia time, and minimum oxygen saturation (SaO2) significantly correlated with IL-6 and CRP levels, but apnea-hypopnea index did not. When stratified by body mass index (BMI) category, OSA severity was associated with IL-6 levels in obese participants only (BMI > 30 kg/m2). A multiple linear regression model with interaction terms showed an independent association of OSA severity with IL-6 levels and an interaction between OSA severity and BMI, i.e., degree of obesity altered the relationship between OSA and IL-6 levels. An independent association of OSA severity with CRP levels was found for minimum SaO2 only. A similar interaction of OSA severity and BMI on CRP levels was found for males and postmenopausal women.
OSA severity is an independent predictor of levels of IL-6 and CRP but interacts with obesity such that this association is found only in obese patients.
Arnardottir ES; Maislin G; Schwab RJ; Staley B; Benediktsdottir B; Olafsson I; Juliusson S; Romer M; Gislason T; Pack AI. The interaction of obstructive sleep apnea and obesity on the inflammatory markers c-reactive protein and interleukin-6: the Icelandic Sleep Apnea Cohort. SLEEP 2012;35(7):921-932.